The transport of health-related organic micropollutans has been a major water quality and environmental issue in the past few decades. Because of their high toxicity, long environmental half-life and high bioaccumulation factors, many of the hydrophobic organic pollutants (HOPs) are listed as priority pollutants in many countries. Although not all of the chemical and physical factors should be considered in the fate of transportation of all chemicals, a simple one-dimensional mathematical model used to simulate all of the factors was conceptually developed (Bobba et al., 1996). In that study, most important parameters needed in the model were empirically fitted. For numerical simulation of the behaviors of pollutants in the environment, it is important to provide a feasible chemical and physical transport mechanism to describe the geo-chemical and geophysical interactions involved in the system. In this study a general two-dimensional hydrodynamic numerical simulation model is developed .This model can readily extend to a three-dimensional one. The model includes all possible physical and chemical factors that might affect the transport of the pollutants. For validation and demonstration purpose, only sorption-desorption between specified dissolved organic material and phase are studied in the present study. The hydrodynamic model is verified by comparing with the reported numerical results. The numerical model then incorporates the sorption-desorption terms and the sediment effects. From the results of the simulation, the sorption-desorption mechanism and sediment scavenge effect are founded to significantly affects the pollutants fate and transport of an outfall discharge.

No description available.

No description available.

Zugleich: Diss. techn. Wiss. ETH Zürich, 1999. / Literaturverz.

Techn. Universiẗat, Diss., 2000--Berlin.

Techn. Universiẗat, Diss., 2003--Berlin.

Techn. Hochsch., Diss., 2003--Aachen.

Universiẗat, Diss., 2005--Bonn.

The potential of utilizing a new form of chemical processing technology called SpinChem® Rotating Bed Reactor (RBR), in combination with different reactive materials, for the purpose of remediating multi-contaminated aquifers under changing environmental conditions, was investigated using laboratory studies and geochemical models. Four different reactive materials, or combinations thereof, were tested: heat-treated peat powder combined with zero-valent iron (ZVI); IronPeat, which consists of peat powder coated with a ferriferous hydrosol (FFH); and a powdered steel waste product. Results showed that the powdered steel waste was compatible with the technology while the peat-based sorbents were not. However, there were no indications that the kinetics of the sorption reactions increased. This was attributed to the fact that the rate-limiting steps, for the binding of the studied metal(loid)s onto iron oxide, are generally considered to be dependent on the later stages of the sorption process related to diffusion mechanisms and not to the rate of mass transfer through the bulk liquid phase, which is what primarily is increased through application of the SpinChem® RBR technology.

Microbial actions on coal have long been identified as a source of methane in coalbeds. Andrew Scott (1995) was the first to propose imitating the natural process of biogenic gasification, possibly leading to recharging coalbed methane (CBM) reservoirs, or setting up natural gas reservoirs in non-producing coalbeds. This study was aimed at identifying the changes in coal properties that affect gas deliverability in coal-gas reservoirs, when treated with microbial consortia to generate/enhance gas production. The experimental work tested the sorption and diffusion properties for the coal treated and, more importantly, the variation in the relevant parameters with continued bio-conversion since these are the first two phenomena in CBM production. During the first phase, single component sorption-diffusion experiments were carried out using pure methane and CO2 on virgin/baseline coals, retrieved from the Illinois basin. Coals were then treated with nutrient amended microbial consortia for different periods. Gas production was monitored at the end of thirty and sixty days of treatment, after which, sorption-diffusion experiments were repeated on treated coals, thus establishing a trend over the sixty-day period. The sorption data was characterized using Langmuir pressure and volume constants, obtained by fitting it over the Langmuir isotherm. The diffusion coefficient, D, was estimated by establishing the variation trend as a function of pore pressure. The pressure parameter was considered critical since, with continued production of methane, the produced gas diffuses into the coal matrix, where it gets adsorbed with increasing pressure. During production, the pressure decreases and the process is reversed, gas diffusing out of the coal matrix and arriving at the cleat system. The results indicated an increase in the sorption capacity of coal as a result of bioconversion. This was attributed to increased pore surface areas as a result of microbial actions. However, significant hysteresis was observed during desorption of methane and was attributed to preferential desorption from sorption sites in the pathways leading to pore cavities. This is corroborated by the increased rates of diffusion, especially for methane, which exhibited rates higher than that for CO2. This contradicted the results for untreated/baseline coal, which were in agreement with previous studies. Effort was made to explain this anomaly by the non-monotonic dependence of effective diffusion coefficient on the size of the diffusing particles, where in coalbed environments, CO2 has smaller kinetic diameter than methane.